The US on Monday reopens its land and air borders to foreign visitors who are fully vaccinated against Covid-19, ending 20 months of restrictions on travel that separated families, harmed tourism and strained diplomatic ties.
The restrictions were particularly unpopular in Europe and US neighbours Canada and Mexico.
To slow the spread of the coronavirus, US borders were closed after March 2020 to travellers from large parts of the world, including the EU, Britain and China, India and Brazil. Overland visitors from Mexico and Canada were also banned.
The months of restrictions affecting hundreds of millions of people caused personal and economic suffering during the Covid-19 pandemic.
"It's been so hard," Alison Henry, 63, told AFP. "I just want to see my son."
The British woman plans to fly on Monday to see her son in New York after 20 months of separation.
Families on both sides of the Atlantic are eager to finally reunite with their loved ones.
Although travel from the US to Europe has been possible since summer, foreign US residents holding certain visas had no guarantee of being able to re-enter the country.
To cope with surging demand, airlines have increased the number of transatlantic flights and plan to use larger planes.
Along the border with Mexico, many cities in the US states of Texas and California have faced economic struggles because of anti-Covid trade restrictions.
Canada to Florida
Meanwhile, Canadian seniors will be able to resume their annual car trips to Florida to escape the bitter northern winters.
But the cost of the PCR tests Canada is requiring for cross-border travel – up to $250 each – can be prohibitive.
Ann Patchett, an Ontario resident, told the Ottawa Citizen that it will cost $500 for her and her husband to go south to visit family.
"Do you want to hug your children? Do you want to tuck your grandchildren into bed? It's very frustrating," Ms Patchett said.
New York congressman Brian Higgins, whose district touches the Canadian border and includes the US side of Niagara Falls, will on Monday join mayors from both countries to call on Canada to drop its testing requirement.
Lifting the travel ban will affect more than 30 countries. But entry into the US will not be totally unregulated.
Authorities plan to closely monitor travellers' vaccination status and will still require them to present negative Covid-19 test results.
The US, from Monday, will require air passengers to be fully vaccinated and tested within three days before travel. Airlines will be required to put in place a contact-tracing system.
The land border opening will happen in two phases.
Starting on Monday, vaccines will be required for "non-essential" trips such as family visits or tourism, although unvaccinated travellers will still be allowed into the country for "essential" trips, as they have been for the past 18 months.
A second phase, starting in early January, will require all visitors to be fully vaccinated to enter the US by land, no matter the reason for their trip.
US health authorities have said all vaccines approved by the US Food and Drug Administration and the World Health Organisation would be accepted for entry by air.
At the moment, this includes the AstraZeneca-Oxford, Johnson & Johnson, Moderna, Pfizer/BioNTech, Covaxin, Sinopharm and Sinovac vaccines.
The US has not yet commented on the increase in Covid-19 cases in Europe.
'Grave concern' over Europe
The WHO has expressed "grave concern" over the rising pace of infections in Europe, warning that the current trajectory could mean "another half a million Covid-19 deaths" by February.
But US Surgeon General Vivek Murthy on Sunday told ABC that he was "cautiously optimistic about where we are.
"We can't take our foot off the accelerator until we're at the finish line," Dr Murthy said.
But in Berlin, Elisabeth Zours, 51, is ready to roll.
A lifelong Rolling Stones fan, Ms Zours had to miss a St Louis show by the rock super group in September because of Covid-19 restrictions and was "frustrated" by the slow US reopening.
Now she plans to make up for lost time.
"I've got tickets for four [US] concerts," Ms Zours said. "Their music is like a good friend."